Ensure loose text trims to non-empty in dashboard card title discovery

[cscheid]

Closes #11549.

[cscheid]

Before we merge this, we still need to fix the color of the outline in the tab itself.

[cderv]

we still need to fix the color of the outline in the tab itself.

See comment at #11549 (comment)

and related issue

• $table-border-color is now white by default due to $border-color computation which impact various elements (callout, tables, kdb, ..) #11561